Lithographic apparatus and device manufacturing method

Abstract

A lithographic apparatus includes an illumination system configured to provide a beam of radiation and projection system configured to project the radiation beam onto a target portion of a substrate. At least one of the illumination system and the projection system includes a focusing element for reflecting or refracting the beam. A plurality of stop discs is provided, each having an aperture therethrough, together with a disc positioner configured to place one of the stop discs adjacent the focusing element to control the numerical aperture (NA) of the projection system or illumination system. The apparatus further includes a disc changer configured to select one of the stop discs and provide the selected stop disc to the disc positioner, the disc changer being external to the projection system or illumination system.

1. A lithographic apparatus, comprising:
 an illumination system configured to provide a beam of radiation; 
 a support configured to support a patterning device, the patterning device configured to impart a pattern to the beam of radiation; 
 a substrate table configured to hold a substrate; 
 a projection system configured to project the patterned beam onto a target portion of the substrate; 
 wherein the illumination system, or the projection system, or both the illumination system and the projection system, includes a focusing element to reflect the beam of radiation, and the apparatus further comprises 
 a disc positioner configured to place a stop disc adjacent the focusing element so that the beam of radiation passes through an aperture in the stop disc; and 
 a disc changer configured to select the stop disc from a plurality of stop discs and supply the selected stop disc to the disc positioner, the disc changer being external to the focusing element, 
 wherein the disc changer and the focusing element are, in use, enclosed within a vacuum. 
 
   
   
     2. An apparatus according to  claim 1 , wherein the focusing element is enclosed within a controlled environment and the disc changer is outside the controlled environment. 
   
   
     3. An apparatus according to  claim 2 , further comprising a disc delivery mechanism configured to deliver the selected stop disc from the disc changer to the disc positioner, wherein the controlled environment comprises one or more valves to allow the disc delivery mechanism to move the disc from the disc changer outside the controlled environment to the disc positioner inside the controlled environment. 
   
   
     4. An apparatus according to  claim 2 , wherein the disc changer is enclosed in a further controlled environment. 
   
   
     5. An apparatus according to  claim 1 , further comprising a magazine associated with the disc changer configured to hold the plurality of stop discs when not in use. 
   
   
     6. An apparatus according to  claim 1 , wherein the disc positioner is configured to place the selected stop disc in the pupil plane of the focusing element. 
   
   
     7. An apparatus according to  claim 1 , wherein, in use, the size of the aperture of the selected stop disc placed adjacent to the focusing element determines the numerical aperture of the focusing element. 
   
   
     8. An apparatus according to  claim 1 , wherein the focusing element is a reflective lens. 
   
   
     9. An apparatus according to  claim 1 , wherein the radiation has a wavelength of between about 5 nm and about 20 nm. 
   
   
     10. An apparatus according to  claim 1 , wherein the radiation has a wavelength of about 193 nm. 
   
   
     11. An apparatus of  claim 1 , wherein both the illumination system and the projection system include a focusing element, and both of the focusing elements are, in use, enclosed within the vacuum. 
   
   
     12. An apparatus of  claim 1 , wherein both the illumination system and the projection system include a focusing element, and only one of the focusing elements is, in use, enclosed within the vacuum. 
   
   
     13. An apparatus of  claim 1 , wherein the entire illumination system is, in use, enclosed within the vacuum. 
   
   
     14. An apparatus of  claim 1 , wherein the entire projection system is, in use, enclosed within the vacuum. 
   
   
     15. An apparatus of  claim 1 , wherein the focusing element comprising a plurality of focusing elements. 
   
   
     16. A device manufacturing method, comprising:
 providing a beam of radiation of radiation using an illumination system; 
 patterning the beam of radiation; 
 projecting the patterned beam of radiation onto a target portion of a substrate at least partially covered by a layer of radiation sensitive material using a projection system; 
 positioning a stop disc adjacent a focusing element of the illumination system or the projection system using a disc positioner so that the beam of radiation passes through an aperture in the stop disc; 
 removing the stop disc from its position adjacent the focusing element using the disc positioner; and 
 replacing the stop disc with a further stop disc using a disc changer to supply the further stop disc to the disc positioner, the disc changer being external to the focusing element, 
 wherein the disc changer and the focusing element are enclosed in a vacuum. 
 
   
   
     17. A method according to  claim 16 , wherein whichever of the projection system or the illumination system comprises the focusing element is enclosed in a controlled environment and the disc changer is external to the controlled environment. 
   
   
     18. A method according to  claim 17 , further comprising removing the stop disc from the controlled environment by way of a valve and inserting the further stop disc through the valve into the controlled environment. 
   
   
     19. A method according to  claim 17 , wherein the disc changer is enclosed in a further controlled environment. 
   
   
     20. A method according to  claim 16 , wherein the disc changer comprises a magazine configured to hold a plurality of stop discs having different apertures. 
   
   
     21. A method according to  claim 16 , wherein the stop disc is positioned in a pupil plane of the focusing element. 
   
   
     22. A method according to  claim 16 , wherein the size of the aperture of the stop disc positioned adjacent the lens determines the numerical aperture of the focusing element. 
   
   
     23. A method according to  claim 16 , wherein the focusing element is a reflective lens. 
   
   
     24. A method according to  claim 16 , wherein the radiation has a wavelength between about 5 nm and about 20 nm. 
   
   
     25. A method according to  claim 16 , wherein the radiation has a wavelength of about 193 nm. 
   
   
     26. A method of  claim 16 , wherein both the illumination system and the projection system include a focusing element, and both of the focusing elements are, in use, enclosed within the vacuum. 
   
   
     27. A method of  claim 16 , wherein both the illumination system and the projection system include a focusing element, and only one of the focusing elements is, in use, enclosed within the vacuum. 
   
   
     28. A lithographic apparatus, comprising:
 an illumination system configured to provide a beam of radiation; 
 a support configured to support a patterning device, the patterning device configured to impart a pattern to the beam of radiation; 
 a substrate table configured to hold a substrate; 
 a projection system configured to project the patterned beam onto a target portion of the substrate and comprising a focusing element to reflect the beam of radiation; 
 a disc positioner configured to place a stop disc adjacent the focusing element so that the beam of radiation passes through an aperture in the stop disc; and 
 a disc changer configured to select the stop disc from a plurality of stop discs and supply the selected stop disc to the disc positioner, the disc changer being external to the projection system, the disc changer and the projection system, in use, enclosed within a vacuum. 
 
   
   
     29. A device manufacturing method, comprising:
 providing a beam of radiation using an illumination system; 
 patterning the beam of radiation; 
 projecting the patterned beam of radiation onto a target portion of a substrate at least partially covered by a layer of radiation sensitive material, the illumination system, or the projection system, or both the illumination system and the projection system, comprising a focusing element to reflect the beam of radiation; 
 selecting a stop disc from a plurality of stop discs using a disc changer to supply the selected stop disc to a disc positioner, the disc changer external to the focusing element; and 
 positioning the stop disc using the disc positioner adjacent the focusing element so that the beam of radiation passes through an aperture in the stop disc, 
 wherein the disc changer and the focusing element are, in use, enclosed in a vacuum. 
 
   
   
     30. A method of  claim 29 , wherein both the illumination system and the projection system include a focusing element, and both of the focusing elements are, in use, enclosed within the vacuum. 
   
   
     31. A method of  claim 29 , wherein both the illumination system and the projection system include a focusing element, and only one of the focusing elements is, in use, enclosed within the vacuum. 
   
   
     32. A lithographic apparatus, comprising:
 an illumination system configured to provide an EUV beam of radiation; 
 a support configured to support a patterning device, the patterning device configured to impart a pattern to the EUV beam of radiation; 
 a substrate table configured to hold a substrate; 
 a projection system configured to project the patterned EUV beam of radiation onto a target portion of the substrate; 
 wherein the illumination system, or the projection system, or both the illumination system and the projection system, includes a focusing element within the EUV beam of radiation to shape and/or filter the EUV beam of radiation, and the apparatus further comprises 
 a disc positioner configured to place a stop disc adjacent the focusing element so that the EUV beam of radiation passes through an aperture in the stop disc; and 
 a disc changer configured to select the stop disc from a plurality of stop discs and supply the selected stop disc to the disc positioner, the disc changer being external to the focusing element, 
 wherein the disc changer and the focusing element are, in use, enclosed within a vacuum. 
 
   
   
     33. An apparatus of  claim 32 , wherein both the illumination system and the projection system include a focusing element, and both of the focusing elements are, in use, enclosed within the vacuum. 
   
   
     34. An apparatus of  claim 32 , wherein both the illumination system and the projection system include a focusing element, and only one of the focusing elements is, in use, enclosed within the vacuum.